The present invention relates to a light-reflecting arrangement, particularly for use in traffic control devices such as roadside markers, or the type wherein the period during which the light-reflecting arrangement keeps its light-reflecting properties is extended by insuring that the light-reflecting surface which is presented to view of drivers of oncoming traffic is free of obscuring impurities.
It is well known that the light-reflecting surfaces of traffic signs, roadside markers or other traffic control or guidance devices become obscured during the use of such devices by deposition of dust, dirt, mud and other obscuring impurities thereon. Therefore, it is necessary to periodically remove such obscuring impurities by washing or otherwise cleansing the affected surfaces of such traffic control devices. This can be done either manually or by means of a washing or cleaning apparatus mounted on a vehicle. However, this is rather expensive, particularly in view of the fact that such traffic control devices are widely distributed along the highway network, which means that the roadway sign maintenance personnel has to periodically travel long distances until all of the widely distributed traffic control devices are cleansed.
To alleviate this situation, it has been proposed, in the German application No. 22 25 307 laid open for public inspection, to provide an automatic cleaning arrangement for use in traffic control devices which utilizes an endless band constituted by a transparent foil as a protective film, the band being advanced by a spring-energized motor and passing in front of the light-reflecting surface of the light-reflecting arrangement during its advancement. Then, those portions of the endless band which have passed in front of the light-reflecting surface are passed through a cleansing bath before they are returned, in their cleansed condition, to their position of juxtaposition with the light-reflecting surface. As advantageous as this prior-art arrangement may be in some respects, it is disadvantageous in certain other respects. So, for instance, because of the use of the transparent foil, which is quite sensitive to a mechanical damage and likely to deteriorate when exposed to the ravages of weather, the life span of the endless band is quite limited. Furthermore, the band merely shields the light-reflecting surface but does not completely prevent penetratation of dust particles and the like toward the light-reflecting surface where such obscuring impurities could still deposit and thus interfere with the light-reflcting capability of this light-reflecting surface. This, of course, is very disadvantageous.